Cutting tool bit and holder



March 21, 1961 D. s. SAXMAN CUTTING TOOL BIT AND HOLDER Filed June 6, 1958 hzbi,

INVENTOR. DUANE 15. SAX/WAN.

K M. w 55 &- EN R m m T WA 0,7 m B 0 m m J s M United States Patent CUTTING TOOL BIT AND HOLDER Duane S. Saxman, Bedford, Pa., assignor to Kennametal Inc., Latrobe, Pa., a corporation of Pennsylvania Filed June 6, 1958, Ser. No. 740,348

2 Claims. (Cl. 262-33) This invention relates to a cutting tool bit, andv more particularly to a cutting tool bit adapted to be tightly fitted within a receiving socket of different conformations of a carrying means for the tool bit and tapped in and out of the socket for attaching and releasing it.

The sockets of the carrying means for the tools are usually generally of rectangular configuration in cross section with the top and bottom walls thereof slightly tapered for wedging the shank of the tool bit therein, the shank of the tool bit being also generally of rectangular conformation in cross section with its top and bottom sides slightly tapered in conformity with the tapered inclination of the top and bottom walls of the socket. With the taper of the sides of the shank of the tool bit in exact conformity with that of the top and bottom walls of the socket, the elements properly mate with the surfaces of said parts in line contact so that the tool bit is tightly fitted without rocking and tilting in a vertical plane and working loose. If not tightly fitted the tool bit is subject to being sheared or broken off with the consequent result of the broken parts becoming wedged in the socket or between the work object and the carrier for the tool support. However, it is almost impossible to have the parts accurately tapered to effect a mating or tight fitting relationship, but no way has heretofore been found to overcome this problem in a simple and effective manner.

It has been found that if at least two point or line contact be obtaianed between the bottom wall of the socket and the bottom side of the shank of the tool bit, along the length, effective tight fitting assembly can be assured with only one point contact between the top side of the shank of the tool bit and the top wall of the socket,

irrespective of the conformation, employing the well known principle of a three point support in lieu of four or more point support. This is efiected simply by longitudinally arching or arcing the top wall of the shank of the tool bit.

Accordingly, one of the main objects of the invention is a tool bit which is simple in construction and efiicient in operation.

Another object of the invention is a tool bit having the top side of the shank arched or arced longitudinally.

Another object of the invention is a tool bit with a shank having a supporting bottom side adapted to provide line or multiple point contact with the bottom wall of a socket and maintained in such contact by a point contact portion on the top side.

Another object of the invention is a tool bit adapted to fit sockets with normal manufacturing variations.

Another object of the invention is a tool bit with a shank adapted to provide line or multiple point contact on the supporting side and one point contact on its opposite side.

' Further objects, and objects relating to details of construction and economies of operation, will readily appear from the detailed description to follow. In one instance, the objects of the invention have been accomplished by the device and means set forth in the following specification. The invention is clearly defined and pointed out in the appended claims. A structure constituting a preferred embodiment of the invention is illustrated in the accompanying drawings, forming a part of this specification, in which:

Fig. 1 is a perspective view of a cutting tool embodying the invention. e

Fig. 2 is a cross section on line 2-2 of Fig. 1.

Fig. 3 is an end view of a conventional tool carrying device providing with a socket having a fiat transverse top and bottom wall.

Fig. 4 is a side elevation of an assembly of one of the carrying devices and the tool bit embodying the present invention.

Referring specifically to the drawings in which like numerals designate like parts, numeral 2 is a tool bit having a head 3 with a cutting insert 4 seated within a recess 5 formed on the top side and fastened thereto in any conventional manner, as by brazing. An elongated shank 6 extends from the head, said shank having a top side? which is arched or arced longitudinally to provide a higher portion 8 about midway between two lower end portions 9 and 10. The bottom side of the shank 6 has a longitudinal flat portion 12 extending along its entire length to merge into the heel portion 13 of the head.

A tool of construction described is adapted to be inserted within a socket of a carrying device to provide line contact with the bottom wall of the socket and point contact with the top wall of said socket. Accordingly, a tight fitting relationship in the assembly is effected without having the top and bottom sides of the shank of the tool support conforming to the taper of the top and bottorn Walls of the socket in the carrying member. The bottom wall of the socket is ordinarily transversely flat and extends longitudinally in a straight line, preferably inclined, but, whatever its shape, the bottom flat portion 12 of the shank of the tool bit will provide line contact therewith.

The length of the shank 6 of the tool bit advantageously extends slightly beyond the rear open end 16 of the socket 17 in the conventional carrying means 18'. The tool bit is tapped into the socket with a hammer and is securely held therein without need of further fastening means. Likewise, the tool bit may be advantageously released from the socket 17 by tapping, with a hammer, the rear end of the shank which extends beyond the rear open end 19 of the socket.

The carrying means 18 ('Fig. 3) shows the top wall 21 of the socket to be fiat transversely and as well as the bottom wall 22 thereof. Both of the top and bottom walls of the socket 17 are slightly inclined towards each other from the front to the rear end to provide a wedging action against the top and bottom sides of the shank of the tool bit, the top wall being inclined downwardly and the bottom being inclined upwardly.

As will be seen from the foregoing description, the novel tool bit is adapted to be tightly assembled and fitted to the carrying device. The side walls of the socket serve no function except possibly for confining the tool bit in position.

While the tool bit of this novel construction is suitable for any carrying means, it is particularly suitable for those in rotary type construction mining machines where the tool bits need to be frequently changed and it is desirable to have a construction in which the tool bits may be changed in the carrying means as quickly and expeditiously as possible.

The higher portion 8 on the top side of the shank 6 is, as above described, about midway between A the opposite ends of the shank, exclusive of the head 3. It is preferable that the arc of the arced top side of the shank be described through points 9 and 10 on the top side of Patented Mar. 21, 1961- the shank, near the opposite ends of the shank, to be about midway and provide a tangential point with the fiat top wall 21 (Fig. 3) of the socket about midway of the length of the socket.

- The bottom flat side 12 of the tool bit is in a straight line throughout itslength to provide line contact, or at least none of the intermediate portions between the heel and the opposite end extend below to prevent a line or two or more point cont-act. 7

It will be understood that there may be various changes in details of construction without departing from the spirit of the invention, and therefore, the invention is claimed broadly as indicatedby the appended claims.

Having thus described my invention, what I claim as new and useful and desire to secure by US. Letters Patent is:

1. In a tool holder having a socket of generally rectangular configuration in cross section and including a pair of opposite substantially flat walls for wedging the shank of a tool bit therein; the combination therewith of a cutting tool bit comprising an elongated shank of generally rectangular configuration in cross section, said shank having opposite sides adapted to cooperate respectively with said pair of opposite walls of said socket, one

of said sides of said shank being arched longitudinally and having tangential point contact with the adjacent wall of said socket and the: opposite side of said shank being substantially fiat and extending longitudinally of said shank in a straight line and providing line contact with the wall of said socket adjacent to it for tightly fitting said tool bit within said socket.

2. The combination of claim 1 wherein the high point of said arched side of said shank is so located to provide said tangential point contact with said socket approximately midway between opposite ends of said shank.

References Cited in the file of this patent UNITED STATES PATENTS 894,184 Buel July 28, 1908 1,679,135 Holmes July 31, 1928 2,190,000 Stenger et al. Feb. 13, 1940 2,289,464 Simmons July 14, 1942 2,322,929 Fulke June 29, 1943 2,647,737 Stephens Aug. 4, 1953 2,722,410 Brown Nov. 1, 1955 2,743,917 Krekeler May 1, 1956 2,798,715 Brown July 9, 1957 

